1. Field of the Invention
The present invention relates to a stringed instrument, a manufacturing method of the stringed instrument, and a stringed instrument manufacturing apparatus.
2. Description of the Related Art
FIGS. 13(a) to 13(c) are structural drawings of a violin as an example of stringed instruments of the present invention. FIG. 13(a) is a front view of the violin, FIG. 13(b) is a right side view of the violin, and FIG. 13(c) is an M-M′ sectional view of the violin illustrated in FIG. 13(b). An arrow 70 defining a longitudinal direction of the violin, an arrow 71 defining a width direction of the violin, and an arrow 72 defining a thickness direction of the violin are drawn in each of FIGS. 13(a), 13(b), 13(c) to simplify the explanation.
In the present description, detailed names of respective portions of the violin are referred to later-described non-patent documents 1, 2, 3, 4. A whole of a violin 1 in FIGS. 13(a) to 13(c) is constituted by an instrument main body 4 and a group of equipped members. The instrument main body 4 is generally constituted by a resonance box portion 2 and a neck portion 3. The group of equipped members is generally constituted by a chin rest 5, a tail-piece 6, a tail-gut 7, an endpin 8, an adjuster 9, a bridge 10, strings 11a, 11b, 11c, 11d, pegs 12a, 12b, 12c, 12d, and a sound post 13, which are equipped at respective places of the instrument main body 4. The resonance box portion 2 is integrally fabricated to include a top plate portion 16 in which two “f” holes 14, 15 are opened, a back plate portion 17, side plate portions 18a, 18b, 18c, 18d, 18e, 18f arranged between the top plate portion 16 and the back plate portion 17, blocks 19a, 19b, 19c, 19d, 19e, 19f, a saddle 20 represented by a dotted line (a hidden line), a bass bar 21, purflings 22a, 22b, 22c, 22d, 22e, 22f, and linings 23a, 23b, 23c, 23d, 23e, 23f. There is a case when the block 19a is called as an upper block, the block 19d is called as a lower block, and the other blocks 19b, 19c, 19e, 19f are called as corner blocks among the blocks 19a, 19b, 19c, 19d, 19e, 19f. The neck portion 3 is constituted to include a neck 50, a fingerboard 51, a nut 52, a scroll 53, and a pegbox 54 in which eight holes to mount the pegs 12a, 12b, 12c, 12d are bored. Note that names such as the neck portion, the resonance box portion, the instrument main body in the present description are defined by the present inventor to simplify an explanation of the present invention. The present invention relates to stringed instruments (acoustic violin and so on) including a violin family (a generic name of violin, viola, cello, contrabass) sounding by using an effect and so on of resonance of sound. Instruments such as a guitar, an ukulele in a type plucking the strings with fingers, a pick, or the like are included in the stringed instruments described in the present description, but the following explanation is made centering on the violin being a typical example of the violin family.
Conventionally, the instrument main body of the violin, particularly the resonance box portion is manufactured by adhering woods cut in approximately predetermined shapes by using adhesive (glue, wood bond, and so on). Basic structures of the stringed instruments other than the violin belonging to the violin family, namely, the viola, the cello, the contrabass are approximately the same as the basic structure of the violin illustrated in FIGS. 13(a) to 13(c). One of major differences when the violin, the viola, the cello, and the contrabass in standard sizes are compared respectively is a size of a dimension.
Besides, an example manufacturing a body structure of a stringed instrument (electric guitar) by an additive fabrication method is disclosed in later-described Patent Document 1. The above-stated stringed instruments disclosed in Patent Document 1 (hereinafter, called as a “conventional stringed instrument”) includes a resonance body structure having the structure of the additive fabrication method while regarding the structure as an annual ring. An example in which an instrument is manufactured by laminating and baking plural thin ceramic plates is disclosed in later-described Patent Document 2 though it is different from a generally known additive fabrication method. In the additive fabrication method in which a three-dimensional structure is formed by a laser sintering of which raw material is powder, an additive fabrication method securing fabrication accuracy desired for the three-dimensional structure manufactured by using plural laser irradiation conditions, and enabling to provide enough strength for the three-dimensional structure is disclosed in later-described Patent Document 3. A detailed structure, names of respective portions of instruments, and a manufacturing method of a conventional wooden violin are to be referred to the later-described non-patent documents 1, 2, 3, 4. A general consideration as for the additive fabrication method is to be referred to the later-described non-patent documents 5, 6, 7, and so on.    Patent Document 1: Japanese Patent Public disclosure No. 2004-69928 (refer to paragraphs 0007, 0008 and FIG. 2)    Patent Document 2: Japanese Patent Public disclosure No. 1985-158489    Patent Document 3: Japanese Patent Public disclosure No. 2003-321704    Non-Patent Document 1: “New Technology Series: Violin Making” written by Shoichiro Kawakami, Bijutsu Shuppan. Co., Ltd., Aug. 10, 1992, Second impression    Non-Patent Document 2, “Violin making as it was and is: First part” written by Heron Allen, translated by Remona Oku, Bunkyo Gakki Co., Ltd., Planning Section, July, 1992, Fourth edition    Non-Patent Document 3: “Violin making as it was and is: Second part” written by Heron Allen, translated by Remona Oku, Bunkyo Gakki Co., Ltd., Planning Section, February, 1998, Third edition.    Non-Patent Document 4: “Violin making as it was and is: Third part” written by Heron Allen, translated by Remona Oku, Bunkyo Gakki Co., Ltd., Planning Section, October, 1995, First edition    Non-Patent Document 5: “Three-dimensional CAD Practical Utilization”, edited by Japan Society for Design Engineering, Corona Co., Ltd., First edition, First impression, 2006. 8. 28, pp. 178-190    Non-Patent Document 6: “Rapid Prototyping, Rapid Tooling”, written by Masato Imamura, Journal of the Japan Society of Mechanical Engineers, Vol. 109, No. 1054, 2006. 9, pp. 742-743    Non-Patent Document 7: “Special Issue: Advanced Product Design to using Rapid Prototyping Technology”, Journal of Japan Society for Design Engineering, Vol. 41, No. 12, 2006. 12, pp. 601-629    Non-Patent Document 8: “Aria eighty years old” written by Hideo Itokawa, Nesuko, Jul. 5, 1992, First volume
Here, a subject is returned to the conventional stringed instrument. As stated above, the conventional stringed instrument is manufactured by the additive fabrication method, and has the resonance body structure regarding a lamination structure thereof as an annual ring. However, sound of the stringed instrument is not determined only by the annual ring even though the lamination structure of a structure fabricated by the additive fabrication method can be regarded as the annual ring. When materials constituting a resonance body structure are compared between wood and synthetic resin material, vibrational characteristics (for example, natural resonance frequency, vibrational mode, vibrational amplitude) of both must be different because material constants of the both are different even if shapes (annual ring structure) of the both can be constituted similarly. It is impossible to produce acousmato equivalent to the acousmato of the wooden stringed instrument by the conventional stringed instruments even if the annual ring structure thereof can be imitated, as long as there is the difference in the vibrational characteristics. The inventor of the present invention recognized that it is extremely difficult to obtain the same acousmato as the wooden stringed instrument because there is the difference in the vibrational characteristics as stated above even if the stringed instrument having the same shape as the wooden stringed instrument can be manufactured by using a material different from wood (for example, synthetic resin powder). The inventor looked at from a different angle to get an idea that it is necessary to keep an eye on obtaining the acousmato different from the wooden stringed instruments, or the acousmato difficult to be produced by the wooden stringed instrument if the stringed instrument (particularly the resonance box portion) is manufactured by using the additive fabrication method. For example, the inventor hit upon ideas of manufacturing a violin of which sound emitted by the strings of the violin is different from a general sound, and producing a violin of which sound volumes of respective four strings are extremely small, in addition to manufacture a violin structure copying the structure of the wooden stringed instrument. For example, it is cited to make the sound of a first string (E string, the thinnest string) mellower as an example of the former idea. There are many players to make a sound of E (mi in C major) which is played open in case of the first string (E string, the thinnest string) by pressing a high position of a second string which is said to have a sound mellower than the first string by fingers. It is because it is generally thought that the mellower sound can be created by the second string than, the first string if the sound is the same though there are individual differences in sound preferences. If it is possible to approximate the sound of the first string to that of the second string to satisfy the preference of the player, the first string becomes easier to use, and particularly, it is advantageous to a performance beginner. As an example of the latter idea, it is possible to practice without paying any attention to circumstances if the sound volume created from each of the four strings is extremely small, and therefore, it is very convenient to satisfy purposes of performance such as the performance practice at night and a performance practice performed simultaneously with the other players. A problem to be solved by the present invention exists in providing a stringed instrument capable of corresponding to the preference of the player (user) of the stringed instrument, the purpose of the performance, and so on as much as possible.